Abstract : This invention relates to an aircraft self-protection warning system and particularly to such a system utilizing radar. Yet more particularly, the invention relates to a warning system having the ability to simultaneously maintain surveillance both fore and aft with a single radar. Conventional radar systems for aircraft warning protection have either depended upon a forward-looking radar only or have had separate radar units for rear or side coverage. The forward-looking systems have been housed in the forward nosecone with little or no external portions to cause aerodynamic drag. Side and rear installations, however, almost invariably have required structures outside of the normal aerodynamic surfaces of the aircraft. Because such installations require modifications of the airframe, the provision of such additional protection has been resisted. It is an object of this invention to provide a radar unit having a pattern of waves radiating in one direction and a portion of such pattern intercepted by means reflecting a portion of said waves in the opposite direction. it is further object of the present invention to provide fore and aft protection in a single radar unit confined within the conventional nosecone radome of an aircraft.